Modern petroleum refineries are controlled by advanced process control systems. These process control systems can perform a number of functions, including optimizing the process and identifying abnormal events in the operation of the plant.
Events and disturbances of various magnitudes are constantly affecting process operations. Most of the time, these events and disturbances are handled by the process control system. However, a human operator will sometimes need to intervene in the process operations when the process control system cannot adequately handle an abnormal event. Human intervention is initiated by notifying the console operator of the abnormal situation through alert messages. Alert messages are triggered when certain process measurements violate predefined operating ranges and/or correlations. Early identification of these abnormal events enables the operations team to intervene before the problem escalates into a more severe incident.
In many cases, the identification of abnormal events is performed by expert systems. Expert systems are computerized tools designed to assist the plant operators in making decisions about how to operate the industrial plant. Two commonly used types of expert systems are model-based expert systems and rule-based expert systems.